Lime kiln

Abstract

The utility model discloses a lime kiln which is characterized in that a hearth is vertically and fixedly mounted, the bottom of the hearth is connected with an ash bucket, and an ash bucket ash discharger is arranged at the bottom of the ash bucket; the combustion assembly is fixed to the bottom of the hearth and penetrates through the ash hopper to inject natural gas into the hearth, the stone powder input assembly is fixed to the bottom of the hearth and injects limestone powder particles into the top of the hearth, and the heated limestone powder particles are settled to a pyrolysis ash bed at the bottom of the hearth against flue gas flow. Discharging the lime finished product after continuous pyrolysis through an ash hopper ash discharger; an over-fire air nozzle is arranged on the upper portion of the hearth, and after being burnt out, smoke passes through a smoke-powder separator and then is discharged from a smoke outlet. By means of the technical scheme, high power consumption of a traditional rotary kiln is avoided, the yield of lime and the utilization rate of raw ore can be improved, and meanwhile the treatment cost of tail end flue gas denitration is also avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of lime calcining kilns, in particular to a lime kiln. Background Art

[0002] Lime is usually burned in a vertical kiln or a rotary kiln, and the raw material is limestone with a particle size larger than a few centimeters. The following defects are common:

[0003] 1. Since larger stones are not easy to burn through, in order to avoid "under-burning" inside the stone, the temperature of the calcining zone (firing area) in the kiln will reach 1200-1300℃, which will cause "over-burning" of the outside of the lime block.

[0004] 2. Since the temperature control accuracy of the burning zone is not high and it is difficult to ensure consistency, the current production process is difficult to resolve the contradiction between underburning and overburning. As a result, the proportion of underburning and overburning in the products is generally high, affecting the quality of the lime.

[0005] 3. In order to burn through large-grained stones, the stones must stay in the high-temperature zone for a longer time. Therefore, the kiln body is very large, the equipment is expensive, and the heat loss and electricity consumption are high.

[0006] 4. Although all kilns are equipped with end-of-line flue gas desulfurization and denitrification facilities with relatively high operating costs, they are still difficult to adapt to the continuous improvement of environmental protection standards due to the limitations of process conditions and temperature.

[0007] 5. Stones with a particle size of less than 20 mm that are not suitable for the kiln are thrown away, affecting the utilization rate of the original ore. Utility Model Content

[0008] In response to the above problems, the utility model provides a vertically installed lime kiln. The fixed kiln body avoids the high power consumption of driving the rotary kiln. The limestone powder particles are first sprayed upward downstream under the flame formed by the combustion component, and then settle to the pyrolysis ash bed against the flue gas flow, which effectively prolongs the residence time of the limestone powder particles in the high-temperature zone. At the same time, it avoids the high power consumption of the blower caused by the high wind resistance of the traditional vertical kiln. Limestone powder particles ≤3mm can be fully pyrolyzed on the pyrolysis ash bed ≤950℃, and the lime yield is very high.

[0009] To achieve the above-mentioned purpose, the utility model provides a lime kiln, comprising: a furnace, a high-temperature zone at the furnace bottom, an ash hopper, a combustion assembly, a stone powder input assembly, a furnace air swirl plate, a burnout air nozzle, a burnout zone, a smoke and powder separator, and a smoke outlet;

[0010] The furnace is fixedly installed vertically, the bottom of the furnace is connected to the ash hopper, an ash hopper ash discharger is provided at the bottom of the ash hopper, the top of the furnace is connected to the smoke and powder separator, and the smoke and powder separator is connected to the smoke outlet;

[0011] The combustion assembly is fixed to the bottom of the furnace relative to the ash hopper, and the combustion assembly injects natural gas and combustion-supporting air into the furnace through the ash hopper;

[0012] The furnace air swirl blade is connected to the furnace air duct of the furnace and is arranged above the high temperature area of ​​the furnace bottom;

[0013] The burnout air nozzle is connected to the burnout air duct of the furnace and is arranged around the furnace wall below the burnout zone on the furnace top;

[0014] The stone powder input assembly is fixed to the bottom of the furnace relative to the ash hopper, and the stone powder input assembly sprays limestone powder particles into the top of the furnace through the ash hopper;

[0015] During the upward spraying process, the limestone powder is wrapped and heated by the gas flame, and the heated limestone powder settles against the flue gas flow to the bottom of the furnace and slightly below the pyrolysis ash bed of the bottom wind swirl plate. The finished lime after continuous pyrolysis is finally discharged from the ash hopper ash discharger.

[0016] The smoke after combustion passes through the smoke powder separator to separate the lime powder, and the smoke that meets the environmental protection standards is discharged from the smoke outlet.

[0017] In the above technical solution, preferably, the two ends of the combustion assembly are respectively a natural gas inlet and a natural gas nozzle, the natural gas inlet is arranged above the limestone powder air inlet below the ash hopper, the natural gas inlet is connected to the natural gas nozzle through a gas pipeline, and a preset number of groups of natural gas nozzles are evenly distributed on the outer edge of the limestone powder air nozzle, so that the gas ejected from the natural gas nozzle is radially distributed in an inverted cone relative to the axis of the furnace, and the injection direction of the natural gas nozzle is at a preset angle relative to the axis of the furnace.

[0018] In the above technical solution, preferably, a furnace air inlet and a furnace air duct are provided on the upper part of the high-temperature zone of the furnace bottom, and the furnace air forms downward-swirling air through the furnace air swirl sheet. Under the action of the downward-swirling air, the natural gas flame can form an upward-swirling high-temperature flame that tightly wraps the limestone powder particles at the bottom center of the furnace.

[0019] In the above technical solution, preferably, the finished lime material of the pyrolysis ash bed slides to the cooling ash bed above the ash hopper, and an ash bed air inlet is provided below the cooling ash bed to blow in ash bed cooling air, and the ash bed cooling air can penetrate the finished lime material and form combustion-supporting air at the bottom of the furnace.

[0020] In the above technical solution, preferably, the ash hopper is provided with an ash hopper air inlet to blow in ash hopper cooling air, and the ash hopper air inlet is provided on the side wall of the ash hopper, so that the ash hopper cooling air can pass through the finished lime material in the ash hopper and form furnace bottom vortex wind through the furnace bottom wind vortex sheet.

[0021] In the above technical solution, preferably, multiple groups of burnout air nozzles are symmetrically and evenly distributed relative to the furnace on the furnace wall below the burnout zone, so as to be able to blow uniform burnout air tangentially into the furnace, so that the gas in the furnace is fully burned.

[0022] In the above technical solution, preferably, the two ends of the stone powder input component are the limestone powder air inlet and the limestone powder air nozzle respectively, the limestone powder air inlet is arranged at the lowest point below the ash hopper, and the limestone powder air nozzle is arranged above the pyrolysis ash bed in the center of the furnace bottom, the limestone powder particles are blown in by the limestone powder air inlet, pass through the pipeline arranged along the central axis of the furnace, and are ejected from the limestone powder air nozzle.

[0023] In the above technical solution, preferably, the excess air coefficient of the high-temperature zone at the bottom of the furnace is less than 1 and is in an oxygen-deficient combustion state. A burnout air inlet and a burnout air duct are provided above the high-temperature zone at the bottom of the furnace. The burnout air is sprayed into the furnace through the burnout air nozzle to fully burn the combustible gas in the furnace.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: through the vertical installation of the lime kiln furnace, there is no need to drive the high power consumption of the rotary kiln, and the limestone powder particles are first sprayed upstream under the flame formed by the combustion component and then settle against the flue gas flow, which effectively prolongs the residence time of the limestone powder particles in the high temperature zone, while avoiding the high power consumption of the blower caused by the high wind resistance of the traditional vertical kiln. After the limestone powder particles settle to the pyrolysis ash bed, they continue to be fully pyrolyzed for a long time, and the lime yield is high. The high-temperature oxygen-deficient combustion at the bottom of the furnace does not produce NOx, and the top burnout zone set at the top of the furnace does not produce high-temperature NOx. Ultra-low NOx emissions can be achieved without the need for terminal flue gas treatment facilities, completely avoiding the operating costs of the terminal flue gas treatment process. In addition, the finished lime has been fully cooled by the cooling air before being discharged from the ash hopper, thereby greatly reducing the heat loss carried away by the finished lime material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic diagram of a cross-sectional structure of a lime kiln disclosed in one embodiment of the present invention.

[0026] In the figure, the corresponding relationship between each component and the reference numeral is as follows:

[0027] 1. Limestone powder air inlet; 2. Limestone powder air nozzle; 3. Natural gas inlet; 4. Natural gas nozzle; 5. Ash bed air inlet; 6. Cooling ash bed; 7. Furnace bottom air swirl vane; 8. Ash hopper; 9. Pyrolysis ash bed; 10. Furnace; 11. Temperature measuring element; 12. Upward swirl flame; 13. Upward spraying stone powder flow; 14. Downward falling stone powder flow; 15. Furnace air swirl vane; 16. Furnace air inlet; 17. Ash hopper air inlet; 18. Ash hopper ash discharger; 19. Furnace air duct; 20. Furnace top burnout zone; 21. Burnout air inlet; 22. Burnout air nozzle; 23. Burnout air duct; 24. Smoke and powder separator; 25. Flue gas outlet; 26. Air lock and ash discharge valve; 27. Ash delivery fan. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0029] The present invention is described in further detail below with reference to the accompanying drawings:

[0030] like Figure 1 As shown, a lime kiln provided by the present invention includes: a furnace 10, an ash hopper 8, a combustion component, a stone powder input component, a smoke and powder separator 24 and a smoke outlet 25;

[0031] The furnace 10 is fixedly installed vertically, the bottom of the furnace 10 is connected to the ash hopper 8, the bottom of the ash hopper 8 is provided with an ash hopper ash discharger 18, the top of the furnace 10 is connected to the smoke and powder separator 24, and the smoke and powder separator 24 is connected to the smoke outlet 25;

[0032] The combustion assembly is fixed to the bottom of the furnace 10 relative to the ash hopper 8, and the combustion assembly sprays natural gas and other fuels and combustion-supporting air into the upper part of the furnace 10 through the ash hopper 8;

[0033] The furnace air swirl blade 15 is connected to the furnace air duct 19 of the furnace 10 and is arranged above the high temperature area of ​​the furnace bottom;

[0034] The burnout air nozzle 22 is connected to the burnout air duct 23 of the furnace 10 and is arranged around the furnace wall below the burnout zone at the furnace top;

[0035] The stone powder input assembly is fixed at the bottom of the furnace 10 relative to the ash hopper 8. The stone powder input assembly can blow limestone particles into the top of the furnace 10 through the ash hopper 8, and at the same time, the flame formed by igniting the fuel can wrap the limestone particles and spray upward;

[0036] During the upward spraying process, the limestone particles are enveloped and heated by the gas flame. The heated limestone particles settle against the flue gas flow to the pyrolysis ash bed 9 at the bottom of the furnace 10, slightly below the bottom wind swirl blades 7, where they undergo continuous pyrolysis to form finished lime material, which is then discharged from the ash hopper 18.

[0037] The smoke after the flame combustion passes through the smoke powder separator 24 to separate the lime powder, and the smoke that meets the standards is discharged from the smoke outlet 25.

[0038] In this embodiment, the vertically installed lime kiln furnace 10 eliminates the need for high power consumption to drive the rotary kiln. The limestone powder particles are first sprayed upward downstream under the flame formed by the combustion component and then settle against the flue gas flow, effectively extending the residence time of the limestone powder particles in the high-temperature zone. At the same time, the high power consumption of the blower caused by the high wind resistance of the traditional vertical kiln is avoided. After the limestone powder particles settle to the pyrolysis ash bed 9, they continue to be fully pyrolyzed for a long time, and the lime yield is high.

[0039] Specifically, during the implementation process, limestone powder particles are sprayed into the furnace 10 through the stone powder input component, and the flame formed by the ignition of the fuel sprayed by the combustion component can wrap around the limestone powder particles for heating. The limestone powder particles continue to move upward under the joint drive of the initial kinetic energy at the time of spraying and the flame heat flow, forming an upper spray stone powder flow 13, and at the same time the flame continues to heat the limestone powder particles.

[0040] After the kinetic energy of the limestone particles is exhausted, they will turn downward under the action of gravity, forming a falling stone powder flow 14. During this process, the rising flue gas flow can prolong the residence time of the limestone particles in the high-temperature flue gas so that they continue to be heated, and finally fall onto the pyrolysis ash bed 9 at the bottom of the furnace 10. The pyrolysis ash bed 9 provides a high-temperature environment for continuous pyrolysis of the limestone particles, eventually forming finished lime materials, which are discharged by the ash hopper discharger 18.

[0041] Furthermore, the high-temperature flue gas after flame combustion is output from the top of furnace 10 to a smoke and dust separator 24, which separates the lime powder from the flue gas. The output end of smoke and dust separator 24 is connected to an air-locking ash discharge valve 26, which is connected to the ash air supply pipe. The separated fine lime powder passes through air-locking ash discharge valve 26 and is transported back to the bottom of furnace 10 under the wind power of ash supply fan 27. The flue gas after low-nitrogen combustion is discharged through flue gas outlet 25, meeting emission standards, for waste heat utilization and dust treatment.

[0042] The combustion component may use natural gas or other gaseous, liquid and solid (including powdered) fuels, but the arrangement and combustion method of the combustion component at the bottom of the furnace 10 must meet the above-mentioned requirements.

[0043] The furnace 10 may have a circular, square or polygonal structure.

[0044] In addition, a temperature measuring element 11 is installed at the bottom edge of the furnace 10 to monitor the temperature inside the furnace 10 .

[0045] In the above embodiment, preferably, the two ends of the combustion assembly are respectively a natural gas inlet 3 and a natural gas nozzle 4. The natural gas inlet 3 is arranged above the limestone powder air inlet 1 below the ash hopper 8. The natural gas inlet 3 is connected to the natural gas nozzle 4 through a gas pipeline. A preset number of groups of natural gas nozzles 4 are evenly distributed on the outer edge of the limestone powder air nozzle 2, so that the gas ejected by the natural gas nozzle 4 is radially distributed in an inverted cone relative to the axis of the furnace 10, and the injection direction of the natural gas nozzle 4 is at a preset angle relative to the axis of the furnace 10.

[0046] Specifically, the combustion assembly is designed to feed fuel into furnace 10, ignite it, and form a flame. This requires that a section of the natural gas nozzle 4 be angled with the limestone powder input assembly, preferably within a range of 30 to 45 degrees, so that the fuel flame can envelop and heat the limestone particles. In practice, the external natural gas inlet 3 can be configured to match the combustion assembly's structure, fuel type, and characteristics. The specific configuration of the natural gas inlet 3, including its bending pattern, bending angle, inlet height, inlet position, and pipe diameter, can be adjusted as needed and is not limited herein.

[0047] In the above embodiment, preferably, a furnace air inlet 16 and a furnace air duct 19 are provided on the upper part of the high-temperature zone of the furnace bottom, and the furnace air passes through the furnace air swirl plate 15 to form downward swirling air. Under the action of the downward swirling air, the natural gas flame can form an upward swirling flame 12 tightly wrapped with limestone powder particles at the bottom center of the furnace 10.

[0048] In this embodiment, the ash bed cooling air blown in through the ash bed air inlet 5 can cool down the limestone powder particles on the pyrolysis ash bed 9. At the same time, the heated air passes through the furnace bottom wind swirl plate 7 to form an upward swirling combustion-supporting air that blows toward the upper part of the furnace 10, providing combustion support for the newly input fuel.

[0049] In the above embodiment, preferably, the finished lime material of the pyrolysis ash bed 9 slides to the cooling ash bed 6 above the ash hopper 8, and an ash bed air inlet 5 is provided below the cooling ash bed 6 to blow in ash bed cooling air. The ash bed cooling air can penetrate the finished lime material and form combustion-supporting air at the bottom of the furnace.

[0050] In the above embodiment, preferably, the ash hopper 8 is provided with an ash hopper air inlet 17 to blow in the ash hopper cooling air, and the ash hopper air inlet 17 is provided on the side wall of the ash hopper 8, so that the ash hopper cooling air can pass through the finished lime material in the ash hopper 8 and form the bottom vortex wind through the bottom wind vortex sheet 7.

[0051] In this embodiment, the ash hopper air inlet 17 provided on the ash hopper 8 is closer to the bottom of the ash hopper 8 than the ash bed air inlet 5. This allows the finished lime material, initially cooled by the ash bed cooling air, to be further cooled by the ash hopper cooling air. After cooling and exchanging heat with the finished lime material, the ash hopper cooling air becomes hot. The ash hopper cooling air mixes upward with the ash bed cooling air and together blows toward the upper portion of the furnace 10, providing a combustion-supporting effect. After being cooled by the ash hopper cooling air, the temperature of the finished lime material is significantly reduced, meeting discharge standards. The material is then discharged through the ash hopper ash discharger 18, completing the lime sintering process from limestone powder.

[0052] In the above embodiment, preferably, multiple groups of burnout air nozzles 22 are symmetrically and evenly distributed relative to the furnace 10 on the furnace wall below the furnace top burnout zone 20, so as to be able to blow uniform burnout air tangentially into the furnace 10, so that the gas in the furnace 10 is fully burned.

[0053] In the above embodiment, preferably, the two ends of the stone powder input component are a limestone powder air inlet 1 and a limestone powder air nozzle 2, respectively. The limestone powder air inlet 1 is arranged at the lowest point below the ash hopper 8, and the limestone powder air nozzle 2 is arranged above the pyrolysis ash bed 9 in the center of the furnace bottom. The limestone powder particles are blown in by the limestone powder air inlet 1, pass through the pipeline arranged along the central axis of the furnace 10, and are ejected by the limestone powder air nozzle 2.

[0054] Specifically, the stone dust input assembly is used to input limestone powder into the furnace 10. This requires that a section of the side of the limestone powder air nozzle 2 be vertically arranged on the central axis of the furnace 10. The limestone powder particles ejected from the centrally located limestone powder air nozzle 2 are bundled and diverge upward, forming an upper stone dust flow 13. During implementation, the specific configuration of the outer limestone powder air inlet 1, such as the bending method, bending angle, inlet height, and inlet position, can be adjusted as needed and are not limited here.

[0055] In the above embodiment, preferably, the excess air coefficient of the high-temperature zone at the bottom of the furnace is less than 1 and is in an oxygen-deficient combustion state. A burnout air inlet 21 and a burnout air duct 23 are provided above the high-temperature zone at the bottom of the furnace. The burnout air is sprayed into the furnace 10 through the burnout air nozzle 22 to fully burn the combustible gas in the furnace.

[0056] In the above embodiment, preferably, a preset number of groups of natural gas nozzles 4 are evenly distributed on the edge of the limestone powder air nozzle 2, or the natural gas nozzles 4 are symmetrically distributed on the edge of the limestone powder air nozzle 2 in the shape of an inverted cone, so that the fuel ejected by the natural gas nozzles 4 is radially distributed relative to the limestone powder particles ejected from the limestone powder air nozzle 2.

[0057] Specifically, the shape and structure of the natural gas nozzle 4 in the furnace 10 can be arranged in two ways:

[0058] One is to evenly distribute multiple fuel transmission channels in a radial pattern, and to place the corresponding natural gas nozzles 4 at a predetermined angle relative to the limestone powder air nozzles 2;

[0059] The second is to use the limestone powder air nozzle 2 as the cone top and set an inverted conical channel as the fuel transmission channel, and the fuel output position, namely the natural gas nozzle 4, is the annular channel opening at the top of the inverted cone.

[0060] Both of the above configurations can form radial flames around the limestone particles, thereby wrapping them upwards and effectively heating them. In specific implementations, the number, cross-sectional shape, and diameter of the fuel transmission channels can be determined based on the above configurations, and are not limited here.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A lime kiln, characterized in that: include: Furnace, furnace bottom high temperature area, ash hopper, combustion assembly, stone powder input assembly, furnace air swirl sheet, burnout air nozzle, burnout area, smoke and powder separator and smoke outlet; The furnace is vertically fixed, the bottom of the furnace is connected to the ash hopper, an ash hopper ash discharger is arranged at the bottom of the ash hopper, the top of the furnace is connected to the smoke and powder separator, and the smoke and powder separator is connected to the smoke outlet; The combustion assembly is fixed to the bottom of the furnace relative to the ash hopper, and the combustion assembly sprays natural gas and combustion-supporting air into the furnace through the ash hopper; The furnace air swirl sheet is connected to the furnace air duct of the furnace and is arranged above the high temperature area of ​​the furnace bottom; The burnout air nozzle is connected to the burnout air duct of the furnace and is arranged around the furnace wall below the burnout zone on the furnace top; The stone powder input assembly is fixed at the bottom of the furnace relative to the ash hopper, and the stone powder input assembly sprays limestone powder particles into the top of the furnace through the ash hopper; The limestone powder is wrapped and heated by the gas flame during the upward spraying process, and the heated limestone powder settles against the flue gas flow to the pyrolysis ash bed at the bottom of the furnace slightly lower than the wind swirl plate at the bottom of the furnace, and the finished lime after continuous pyrolysis is finally discharged from the ash hopper discharger; The smoke after combustion passes through the smoke-powder separator to separate the lime powder, and the smoke that meets the environmental protection standards is discharged from the smoke outlet.

2. The lime kiln according to claim 1, characterized in that: The two ends of the combustion assembly are respectively a natural gas inlet and a natural gas nozzle. The natural gas inlet is arranged above the limestone powder air inlet below the ash hopper. The natural gas inlet is connected to the natural gas nozzle through a gas pipeline. A preset number of groups of natural gas nozzles are evenly distributed on the outer edge of the limestone powder air nozzle, so that the gas sprayed from the natural gas nozzle is radially distributed in an inverted cone relative to the axis of the furnace, and the spray direction of the natural gas nozzle is at a preset angle relative to the axis of the furnace.

3. The lime kiln according to claim 2, characterized in that: A furnace air inlet and a furnace air duct are arranged at the upper part of the high temperature zone of the furnace bottom. The furnace air forms downward swirling air through the furnace air swirl sheets. Under the action of the downward swirling air, the natural gas flame can form an upward swirling high-temperature flame tightly wrapping the limestone powder particles at the bottom center of the furnace.

4. The lime kiln according to claim 3, characterized in that: The finished lime material of the pyrolysis ash bed slides down to the cooling ash bed above the ash hopper. An ash bed air inlet is provided below the cooling ash bed to blow in ash bed cooling air. The ash bed cooling air can penetrate the finished lime material and form furnace bottom combustion-supporting air.

5. The lime kiln according to claim 4, characterized in that: The ash hopper is provided with an ash hopper air inlet for blowing in cooling air from the ash hopper, and the ash hopper air inlet is provided on the side wall of the ash hopper, so that the cooling air from the ash hopper can pass through the finished lime material in the ash hopper and form a furnace bottom vortex wind through the furnace bottom wind vortex sheet.

6. The lime kiln according to claim 5, characterized in that: A plurality of groups of burnout air nozzles are symmetrically and evenly distributed relative to the furnace on the furnace wall below the burnout zone, so as to be able to blow even burnout air tangentially into the furnace, so that the gas in the furnace is fully burned out.

7. The lime kiln according to claim 6, characterized in that: The two ends of the stone powder input component are respectively the limestone powder air inlet and the limestone powder air nozzle. The limestone powder air inlet is arranged at the lowest point below the ash hopper, and the limestone powder air nozzle is arranged above the pyrolysis ash bed at the center of the furnace bottom. The limestone powder particles are blown in from the limestone powder air inlet, pass through the pipeline arranged along the central axis of the furnace, and are ejected from the limestone powder air nozzle.

8. The lime kiln according to claim 7, characterized in that: The excess air coefficient of the high temperature zone at the bottom of the furnace is less than 1 and is in an oxygen-deficient combustion state. A burnout air inlet and a burnout air duct are arranged above the high temperature zone at the bottom of the furnace. The burnout air is sprayed into the furnace through the burnout air nozzle to fully burn out the combustible gas in the furnace.

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